tboarder2602
ArboristSite Lurker
I'm having a problem with a walbro carb on an echo cs440 that I'm working on for a friend and I'm hoping someone on here can help me out.
I've been tinkering with and repairing small and large equipment for about 10 years now and I've probably rebuilt 50 or so carbs by now, so I have a decent amount of experience and haven't seen this problem yet.
The problem the saw is having is not getting any fuel on the low idle circuit in the carb. My friend told me about the problem (which according to him was it just wouldn't idle) after he had already replaced the plug, fuel filter, rebuilt the carb, and replaced the gasket which is between the carb and the plastic plate it mounts to. I figured it just needed to be tuned properly, and maybe he still had the limiter caps on etc.
I got the saw, choked it, locked the throttle and it fired and ran. It was rich on the top end so I leaned it out a bit and it was spot on for the high idle. If you let off the throttle it would die anywhere lower then about 1/2 throttle or a little less. I thought the high idle might be affecting this, so I closed it, counting the turns so I can get the saw back to that mixture when all said and done.
After closing the high idle screw, I was not able to get the saw to run at all on only the low idle. That includes choked, not choked, throttle, no throttle, and adjusting the low idle screw (in about 1/2 turn increments) from about 1/2 turn out, all the way out to when it was almost falling out of the carb.
I figured the orifice from the side of the carb, to the low idle screw seat must be clogged so I took the carb out, cleaned it all up real good and inspected the high and low fuel passages. They both are clean as a whistle. I know the low fuel passage is tiny, but holding the carb out in the sunlight with the side up, it allowed sunlight down through the fuel passages enough to be able to see the mixture screw seats. If you blocked the sun with you hand you could no longer see the seats, so I'm 99% sure they are both fine.
I put the carb back together and ran the saw again (after returning the high idle screw back to where I had it before) with the same results. It just won't idle. It just seems weird, I've had saws which will idle but not run with any throttle because they were starving for fuel, but never encountered a saw which wont idle but runs great at high rpm.
Can anyone tell me if I'm missing something else in the carb, or if the problem lies elsewhere? It's really bugging me, as I'm not one to give up easily, nor have I had a saw get the best of me yet. Any advice is greatly appreciated.
Also as you can see by my sig, I don't own any echos and this is my first time working on one. But a walbro carb is a walbro carb no matter what saw its on.
Thanks.
I've been tinkering with and repairing small and large equipment for about 10 years now and I've probably rebuilt 50 or so carbs by now, so I have a decent amount of experience and haven't seen this problem yet.
The problem the saw is having is not getting any fuel on the low idle circuit in the carb. My friend told me about the problem (which according to him was it just wouldn't idle) after he had already replaced the plug, fuel filter, rebuilt the carb, and replaced the gasket which is between the carb and the plastic plate it mounts to. I figured it just needed to be tuned properly, and maybe he still had the limiter caps on etc.
I got the saw, choked it, locked the throttle and it fired and ran. It was rich on the top end so I leaned it out a bit and it was spot on for the high idle. If you let off the throttle it would die anywhere lower then about 1/2 throttle or a little less. I thought the high idle might be affecting this, so I closed it, counting the turns so I can get the saw back to that mixture when all said and done.
After closing the high idle screw, I was not able to get the saw to run at all on only the low idle. That includes choked, not choked, throttle, no throttle, and adjusting the low idle screw (in about 1/2 turn increments) from about 1/2 turn out, all the way out to when it was almost falling out of the carb.
I figured the orifice from the side of the carb, to the low idle screw seat must be clogged so I took the carb out, cleaned it all up real good and inspected the high and low fuel passages. They both are clean as a whistle. I know the low fuel passage is tiny, but holding the carb out in the sunlight with the side up, it allowed sunlight down through the fuel passages enough to be able to see the mixture screw seats. If you blocked the sun with you hand you could no longer see the seats, so I'm 99% sure they are both fine.
I put the carb back together and ran the saw again (after returning the high idle screw back to where I had it before) with the same results. It just won't idle. It just seems weird, I've had saws which will idle but not run with any throttle because they were starving for fuel, but never encountered a saw which wont idle but runs great at high rpm.
Can anyone tell me if I'm missing something else in the carb, or if the problem lies elsewhere? It's really bugging me, as I'm not one to give up easily, nor have I had a saw get the best of me yet. Any advice is greatly appreciated.
Also as you can see by my sig, I don't own any echos and this is my first time working on one. But a walbro carb is a walbro carb no matter what saw its on.
Thanks.
